English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We discuss the Kolmogorov complexity of primordial patches that collapse toform galaxies like the Milky Way; this complexity quantifies the amount ofinitial data available to form the structure. We also speculate on how thequantity changes with time. Because of dark-matter and baryonic collapseprocesses, it likely decreases with time, i.e.\ information sinks dominatesources. But sources of new random information do exist; e.g., a central blackhole with an accretion disk and jets could in principle broadcast small-scalequantum fluctuations over a substantial portion of a galaxy.  A speculative example of how this concept might be useful is indifferentiating between warm (WDM) and cold (CDM) dark matter. With WDM, theinitial patch that formed the Milky Way would have had few features, making thepresent high degree of structure a curiosity. The primordial patch would havehad only several billion independent information-carrying `pixels' if the WDMparticle had a mass of 1 keV. This number of `pixels' is much less than eventhe number of stars in the Milky Way. If the dark matter is proven to be warm,the high degree of structure in the Milky Way could have arisen in two ways:(1) from a high sensitivity to initial conditions, like an intricate fractalarising from a relatively simple computer code; or (2) from random informationgenerated after the galaxy formed, i.e.\ not entirely deterministically fromthe initial conditions.

Kolmogorov complexity in the Milky Way and its reduction with warm dark matter